As device and features size continue to shrink in the semiconductor industry, and also as 3D devices structures (e.g., Intel's Tri-Gate transistor architecture) become more prevalent in integrated circuit (IC) design, the capability of depositing thin conformal films (films of material having a uniform thickness relative to the shape of the underlying structure, even if non-planar) will continue to gain importance. Atomic layer deposition (ALD) is a film forming technique which is well-suited to the deposition of conformal films due to the fact that a single cycle of ALD only deposits a single thin layer of material, the thickness being limited by the amount of one or more film precursor reactants which may adsorb onto the substrate surface (i.e., forming an adsorption-limited layer) prior to the film-forming chemical reaction itself. Multiple “ALD cycles” may then be used to build up a film of the desired thickness, and since each layer is thin and conformal, the resulting film substantially conforms to the shape of the underlying devices structure.
There are many challenges associated with ALD processes, however. Often these challenges have to do with the fact that a single cycle of ALD only deposits a thin adsorption-limited layer, and thus many ALD cycles are required to build up a film of appreciable thickness. Each cycle takes time and requires repeated sequential operation of the apparatus used to accomplish the deposition process. Accordingly, improved methods and apparatuses are sought which improve the speed of wafer processing, and also improve the longevity and maintenance requirements of substrate processing hardware used to perform ALD operations.